The present invention relates to a disposable delivery system for delivering anesthesia. In particular, the present invention relates to a disposable delivery apparatus and method for intraosseously delivering dental anesthesia or anesthesia to other parts of a living body.
The present invention is described in detail below with respect to application of dental anesthesia, but the invention is applicable to delivery of anesthesia or other fluids to other parts of a living body, either human or animal. By describing the invention in detail with respect to delivery of dental anesthesia, the invention is not limited to use only in connection with dental procedures.
Dental anesthesia is generally delivered by injection of a topical anesthetic followed by a deeper injection of anesthetic for desensitizing nerve endings within the region of interest (infiltration) or for blocking off remote sensory nerves which are coupled to the region of interest (nerve blocking).
It is extremely desirable to minimize the amount of anesthesia injected because toxic reactions may result from drug sensitivity or misdirection of the injection needle into the bloodstream. Such risk of toxic reaction is heightened when repeated administration of anesthesia as required, as is often the case with conventional delivery techniques. In addition, conventional administration of anesthesia generally results in numbness of the tongue, cheek, lips and/or even part of the face of the patient for some time after a dental procedure.
As set forth in U.S. Pat. No. 4,944,677 to Alexandre, conventional methods of delivering dental anesthesia include injection into mucous tissue, injection into a ligament, injection into the septum and injection near a nerve-trunk. However, injection into mucous tissue is disadvantageous because it takes a long time for the anesthesia to take effect (about 5 minutes), because the amount of anesthesia is high (about 4 cc), and because adrenalin or another vaso conductor is required for cardiac patients. Injection into a ligament is disadvantageous because it requires high pressure for injection (which causes pain), because injection is into a septic area, because the risk of infection of the ligament is increased, and because the risk of post-operative problems including inflammation and necrosis is increased. Injection into the septum is disadvantageous because it also requires high pressure for injection (which causes pain), because exact positioning of the needle is required, and because injection is into a septic area. And finally, injection into near the nerve-trunk is disadvantageous because there is a long delay in effecting anesthesia (about 10 minutes), because there is a high risk of inadvertent injection into a blood vessel, and because post-operative numbness is very long lasting.
Intraosseous delivery of dental anesthesia directly into the jawbone is also known. Intraosseous delivery is extremely advantageous because it very rapidly achieves numbness limited only to the tooth to be treated, because it enables the amount of anesthetic to be significantly reduced, and because postoperative numbness is essentially avoided.
U.S. Pat. No. 1,539,637 to Bronner discloses a dental instrument adapted for use in penetrating bone structures in order to provide drainage or to inject anesthetics or other fluids. The dental instrument of Bronner essentially comprises a chuck to which a hollow drill may be connected. The dental instrument includes a slidable cleaning pin for preventing cuttings from entering a passage in the hollow drill during bone penetration. Once the hollow drill has penetrated the bone, a syringe is coupled to the dental instrument in order to inject fluid such as an anesthetic. The pressure of the injected fluid causes the cleaning pin to be withdrawn from the interior of the hollow drill to thereby permit the flow of fluid through the passage in the hollow drill into the interior of the bone. The dental instrument of Bronner, however, is cumbersome and cannot remain in place during the performance of a dental procedure, and also does not enable simple re-injection of anesthetic, if and when required, during the performance of a dental procedure.
U.S. Pat. No. 2,317,648 to Siqveland discloses an intraosseous delivery apparatus and method whereby a threaded sleeve is concentrically and removably positioned around a drill bit. The drill bit and threaded sleeve are used together to penetrate the bone, and then the drill bit is detached and withdrawn, leaving the threaded sleeve embedded in the bone as a guide for a hypodermic needle through which anesthesia may be injected. After injection of anesthesia, the threaded sleeve is withdrawn from the bone by reverse rotation. This technique, however, is cumbersome and exacting in that it requires that three small separate elements (i.e., the threaded sleeve, the drill bit and the hypodermic needle) be connected and disconnected during utilization.
U.S. Pat. No. 4,944,677 to Alexandre discloses an intraosseous delivery apparatus and method whereby a smooth, hollow drilling needle is used to drill a hole into the jawbone near the apex of a tooth to be anesthetized. The drilling needle is then removed from the jawbone and a hypodermic needle of substantially the same gauge as the drilling needle is then inserted into the hole formed in the jawbone using a single drop of blood formed during drilling as a marker for entrance to the hole. After the hypodermic needle is inserted into the hole, anesthesia is then delivered by injection directly into the jawbone. This technique, however, is disadvantageous because in actual practice it is very difficult to find the drilled hole and insert the hypodermic needle therein.
U.S. Pat. No. 5,431,655, U.S. Pat. No. 5,484,442 and U.S. Pat. No. 5,601,559, which are related patents and which are all to Melker et al, disclose an intraosseous needle for delivering dental anesthesia. The intraosseous needle has a threaded shaft with a passageway extending substantially therethrough, a solid pointed tip with cutting edges for boring through bone, and two side ports communicating with the passageway. A hub is provided for coupling the needle to a gripping device, and a handle is provided in the shape of a ball knob and is adapted to telescopically and grippingly receive the hub of the needle. The hub and handle are both equipped with mutually engaging torque-transmitting surfaces. After the needle is inserted into the jawbone, anesthesia is delivered via the passageway through the two side ports. This technique, however, avoids the use of a dental drill.